On-chip structure for fiber array alignment by assisting edge coupler index-matching epoxy/oil filling

Abstract

Embodiments of the present disclosure may comprise a system for filling undercuts with an index-matching liquid on a wafer, the system comprising a plurality of edge couplers, each comprising an undercut and a waveguide. Embodiments may also comprise ribs that suspend the waveguide over the undercut. Embodiments may also comprise one or more main buckets and one or more monitor buckets. Embodiments may also comprise a duct that couples together the plurality of edge couplers, the one or more main buckets, and the one or more monitor buckets.

What is claimed is: 
     
         1 . A system for filling undercuts with an index-matching liquid on a wafer or a photonic integrated circuit (PIC), the system comprising:
 a plurality of edge couplers, each comprising
 an undercut; 
 a waveguide, wherein 
 ribs suspend said waveguide over said undercut; 
   one or more main buckets;   one or more monitor buckets; and   a duct, wherein said duct couples together said plurality of edge couplers, said one or more main buckets, and said one or more monitor buckets.   
     
     
         2 . The system of  claim 1 , wherein said index-matching liquid is an oil or an epoxy. 
     
     
         3 . The system of  claim 1 , wherein said one or more main buckets comprise an opening to add said index-matching liquid into said system. 
     
     
         4 . The system of  claim 3 , wherein said opening is the shape of a square with a side length of 0.5 millimeters. 
     
     
         5 . The system of  claim 3 , wherein said opening is the shape of a circle with a diameter of 0.5 millimeters. 
     
     
         6 . The system of  claim 3 , wherein said opening is suitable for said filling with said index-matching liquid by an automatic station. 
     
     
         7 . The system of  claim 1 , wherein said one or more monitor bucket comprise an opening to monitor said filling process. 
     
     
         8 . The system of  claim 1 , wherein a separation distance between at least one of said one or more monitor buckets and at least one of said one or more main buckets is greater than the separation distance between any one of said undercuts and any of said one or more main buckets. 
     
     
         9 . The system of  claim 1 , wherein said plurality of undercuts, said one or more main buckets, and said one or more monitor buckets are formed on a same layer of said wafer. 
     
     
         10 . The system of  claim 1 , wherein said plurality of undercuts, said one or more main buckets, and said one or more monitor buckets are of a same depth. 
     
     
         11 . The system of  claim 1 , wherein said coupling by said duct forms communicating vessels from said plurality of edge couplers, said one or more main buckets, and said one or more monitor buckets. 
     
     
         12 . The system of  claim 1 , wherein said filling of said undercuts with said index-matching liquid increases a mode field diameter at the facet of said waveguides. 
     
     
         13 . The system of  claim 1 , wherein a mode field diameter at the facet of said waveguide is approximately 4 micrometers without said index-matching liquid. 
     
     
         14 . The system of  claim 1 , wherein a mode field diameter at the facet of said waveguide is approximately 9 micrometers with said index-matching liquid. 
     
     
         15 . The system of  claim 1 , wherein a photonic integrated circuit comprises said system. 
     
     
         16 . The system of  claim 1 , wherein said wafer is a silicon photonics wafer. 
     
     
         17 . A method for filling undercuts with an index-matching liquid on a wafer or a photonic integrated circuit (PIC), the method comprising:
 filling a plurality of undercuts, each associated with an edge coupler,   each said edge coupler comprising
 an undercut; 
 a waveguide, wherein 
 ribs suspend said waveguide over said undercut; 
   adding said index-matching liquid to one or more main buckets;   monitor a fill status with one or more monitor buckets; and   distributing said index-matching liquid with a duct, wherein said duct couples together said plurality of edge couplers, said one or more main buckets, and said one or more monitor buckets.   
     
     
         18 . The method of  claim 16 , wherein said index-matching liquid is an oil or an epoxy. 
     
     
         19 . The method of  claim 16 , wherein said one or more main buckets comprise an opening for said adding of said index-matching liquid into said system. 
     
     
         20 . The method of  claim 19 , wherein said opening is the shape of a square with a side length of 0.5 millimeters. 
     
     
         21 . The method of  claim 19 , wherein said opening is the shape of a circle with a diameter of 0.5 millimeters. 
     
     
         22 . The method of  claim 19 , wherein said opening is suitable for said filling with said index-matching liquid by an automatic station. 
     
     
         23 . The method of  claim 16 , wherein said monitoring comprises observing said one or more monitor bucket fill level. 
     
     
         24 . The method of  claim 16 , comprising choosing a separation distance between at least one of said one or more monitor buckets and at least one of said one or more main buckets is greater than the separation distance between any one of said undercuts and any of said one or more main buckets. 
     
     
         25 . The method of  claim 16 , comprising forming said plurality of undercuts, said one or more main buckets, and said one or more monitor buckets on a same layer of said wafer. 
     
     
         26 . The method of  claim 16 , comprising forming said plurality of undercuts, said one or more main buckets, and said one or more monitor buckets of a same depth. 
     
     
         27 . The method of  claim 16 , comprising coupling by said duct said plurality of edge couplers, said one or more main buckets, and said one or more monitor buckets to form communicating vessels. 
     
     
         28 . The method of  claim 16 , comprising increasing a mode field diameter at the facet of said waveguides by filling of said undercuts with said index-matching liquid. 
     
     
         29 . The method of  claim 16 , comprising obtaining a mode field diameter at the facet of said waveguide of approximately 4 micrometers without said index-matching liquid. 
     
     
         30 . The method of  claim 16 , comprising obtaining a mode field diameter at the facet of said waveguide of approximately 9 micrometers with said index-matching liquid.